Wireless power transfer system, methods or devices

ABSTRACT

A wireless power transmission system comprising a wireless power transmitting device and a wireless power receiving device. The wireless power receiving device is configured to enter a cloak state when a temporary pause in power transfer is desired. The wireless power receiving device may allow or deny a communication data stream with the wireless power transmitting device during the cloak state. The wireless power receiving device may request a hot start power transfer phase with the wireless power transmitting device after the cloak state. The wireless power transmitting device may or revert (reset) to a default operating state in the event that a control error packet is received during the cloak state.

FIELD

This relates to a wireless power transfer system, related methods ordevices.

BACKGROUND

In wireless power transfer systems, a wireless power transmitterwirelessly transmits power to a wireless power receiver. The wirelesspower receiver receives the wirelessly transmitted power and providespower to an associated load, such as to an internal battery of anassociated device for charging the battery.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram of an illustrative wireless power systemin accordance with some embodiments.

FIG. 2 is a flow chart of a wireless power transfer protocol which maybe used by the wireless power transfer system of FIG. 1 in someembodiments.

FIG. 3 is a flow chart of a further wireless power transfer protocolwhich may be used by the wireless power transfer system of FIG. 1 insome embodiments.

FIGS. 4 to 12 are graphs showing a timing of communications in thewireless power transfer system of FIG. 1 according to variousembodiments.

DETAILED DESCRIPTION

A wireless power system has a wireless power transmitting device (whichmay also be referred to in some instances as a wireless powertransmitter or an inductive power transmitter) that transmits powerwirelessly to a wireless power receiving device (which may also bereferred to in some instances as a wireless power receiver or aninductive power receiver). The wireless power transmitting device is adevice such as a wireless charging mat, wireless charging puck, wirelesscharging stand, wireless charging table, or other wireless powertransmitting equipment. The wireless power transmitting device may be astand-alone device or built into other electronic devices such as alaptop or tablet computer, cellular telephone or other electronicdevice. The wireless power transmitting device has one or more coilsthat are used in transmitting wireless power to one or more wirelesspower receiving coils in the wireless power receiving device. Thewireless power receiving device is a device such as a cellulartelephone, watch, media player, tablet computer, pair of earbuds, remotecontrol, laptop computer, electronic pencil or stylus, other portableelectronic device, or other wireless power receiving equipment.

During operation, the wireless power transmitting device suppliesalternating-current signals to one or more wireless power transmittingcoils. This causes the coils to generate an alternating magnetic fieldand to transmit alternating-current electromagnetic signals (sometimesreferred to as wireless power signals) to one or more correspondingcoils in the wireless power receiving device. Rectifier circuitry in thewireless power receiving device converts received wireless power signalsinto direct-current (DC) power for powering the wireless power receivingdevice.

The term “coil” may include an electrically conductive structure wherean electrical current generates a magnetic field. For example, inductive“coils” may be electrically conductive wire in three dimensional shapesor two dimensional planar shapes, electrically conductive materialfabricated using printed circuit board (PCB) techniques into threedimensional shapes over plural PCB “layers”, and other coil-like shapes.Other configurations may be used depending on the application. The useof the term “coil”, in either singular or plural, is not meant to berestrictive in this sense.

An illustrative wireless power system is shown in FIG. 1. As shown inFIG. 1, a wireless power system 8 includes a wireless power transmittingdevice 12 (which may also be referred to in some instances as aninductive power transmitter) and one or more wireless power receivingdevices such as wireless power receiving device 10 (which may also bereferred to in some instances as an inductive power receiver). Device 12may be a stand-alone device such as a wireless charging mat, may bebuilt into a laptop or tablet computer, cellular telephone or otherelectronic device, furniture, or may be other wireless chargingequipment. Device 10 is a portable electronic device such as awristwatch, a cellular telephone, a laptop or tablet computer, anelectronic pencil or stylus, or other electronic equipment. Illustrativeconfigurations in which device 12 is a tablet computer or similarelectronic device and in which device 10 is an electronic accessory thatcouples with the tablet computer or similar electronic device duringwireless power transfer operations may sometimes be described herein asexamples. For example, in one example electronic device 12 is a tabletcomputer and electronic device 10 is a stylus configured to attach toelectronic device 12 (tablet) and be wirelessly (e.g., inductively)charged by electronic device 12 (tablet). Illustrative configurations inwhich device 12 is a mat or other equipment that forms a wirelesscharging surface and in which device 10 is a portable electronic deviceor electronic accessory that rests on the wireless charging surfaceduring wireless power transfer operations may also sometimes bedescribed herein as examples.

During operation of system 8, a user places one or more devices 10 on ornear the charging region of device 12. Power transmitting device 12 iscoupled to a source of alternating-current voltage such asalternating-current power source 50 (e.g., a wall outlet that suppliesline power or other source of mains electricity), has a battery such asbattery 38 for supplying power, and/or is coupled to another source ofpower. A power converter such as AC-DC power converter 40 can beincluded to convert power from a mains power source or other alternatingcurrent (AC) power source into DC power that is used to power controlcircuitry 42 and other circuitry in device 12. During operation, controlcircuitry 42 uses wireless power transmitting circuitry 34 and one ormore coils 36 coupled to circuitry 34 to generate an alternatingmagnetic field and to transmit alternating-current wireless powersignals 48 to device 10 and thereby convey wireless power to wirelesspower receiving circuitry 46 of device 10.

Power transmitting circuitry 34 has switching circuitry (e.g.,transistors in an inverter circuit) that are turned on and off based oncontrol signals provided by control circuitry 42 to create AC currentsignals through one or more coils 36. As the AC currents pass through acoil 36 that is being driven by the switching circuitry, a time-varyingmagnetic field (wireless power signals 48) or “flux” is generated, thatis received by one or more corresponding coils 14 electrically connectedto wireless power receiving circuitry 46 in receiving device 10. If thetime-varying magnetic field is magnetically coupled to coil 14, an ACvoltage is induced and a corresponding AC currents flows in coil 14.Rectifier circuitry in circuitry 46 can convert the induced AC voltagein the one or more coils 14 into a DC voltage signals for poweringdevice 10. The DC voltages are used in powering components in device 10such as display 52, touch sensor components and other sensors 54 (e.g.,accelerometers, force sensors, temperature sensors, light sensors,pressure sensors, gas sensors, moisture sensors, magnetic sensors,etc.), wireless communications circuitry 56 for communicating wirelesslywith control circuitry 42 of device 12 and/or other equipment, audiocomponents, and other components (e.g., input-output devices 22 and/orcontrol circuitry 20) and/or are used in charging an internal battery indevice 10 such as battery 18, or to charge subsequent devices, eitherwired or wirelessly.

Devices 12 and 10 include control circuitry 42 and 20. Control circuitry42 and 20 may include storage and processing circuitry such as analoguecircuitry, microprocessors, power management units, baseband processors,digital signal processors, field-programmable gate arrays,microcontrollers, application-specific integrated circuits withprocessing circuits and/or any combination thereof. Control circuitry 42and 20 is configured to execute instructions for implementing desiredcontrol and communications features in system 8. For example, controlcircuitry 42 and/or 20 may be used in selecting a cloaking mode,negotiating a communications data stream during cloaking, initiating ahot start from cloaking, sensing for foreign or other non-receiverobjects (e.g.: metallic objects such as coins or RFID tags withinelectronic devices), determining power transmission levels, processingsensor data, processing user input, processing other information such asinformation on wireless coupling efficiency from transmitting circuitry34, processing information from receiving circuitry 46, usinginformation from circuitry 34 and/or 46 such as signal measurements onoutput circuitry in circuitry 34 and other information from circuitry 34and/or 46 to determine when to start and stop wireless chargingoperations, adjusting charging parameters such as charging frequencies,coil assignments in a multi-coil array, and wireless power transmissionlevels, and performing other control functions. Control circuitry 42and/or 20 may be configured to perform these operations using hardware(e.g., dedicated hardware or circuitry) and/or software (e.g., code thatruns on the hardware of system 8). Software code for performing theseoperations is stored on non-transitory computer readable storage media(e.g., tangible computer readable storage media). The software code maysometimes be referred to as software, data, program instructions,instructions, or code. The non-transitory computer readable storagemedia may include non-volatile memory such as non-volatile random-accessmemory (NVRAM), one or more hard drives (e.g., magnetic drives or solidstate drives), one or more removable flash drives or other removablemedia, other computer readable media, or combinations of these computerreadable media or other storage. Such media may sometimes be referred toherein as electronic memory. Software stored on the non-transitorycomputer readable storage media may be executed on the processingcircuitry of control circuitry 42 and/or 20. The processing circuitrymay include application-specific integrated circuits with processingcircuitry, one or more microprocessors, or other processing circuitry.

Device 12 and/or device 10 may communicate wirelessly. Devices 10 and 12may, for example, have wireless transceiver circuitry in controlcircuitry 42 and 20 (and/or wireless communications circuitry such ascircuitry 56 of FIG. 1) that allows wireless transmission of signalsbetween devices 10 and 12 (e.g., using antennas that are separate fromcoils 36 and 14 to transmit and receive unidirectional or bidirectionalwireless signals, using coils 36 and 14 to transmit and receiveunidirectional or bidirectional wireless signals, etc.). For example,device 12 and/or device 10 may communicate using in-band communicationsinjected or combined into the wireless power signals 48 such as proposedin the Wireless Power Consortium Qi specification 1.2.3, which isincorporated herein by reference. Alternatively, a separate Bluetooth,RFID, NFC, Zigbee, WiFi, RF or other communication system may beemployed. A wireless transmission signal may include a “message” fromone device to the other. A wireless communication message can comprisedata that can be read by control circuitry 42 or 20 of devices 10 or 12.Sending and receiving a “message” is to be interpreted as sending andreceiving a wireless communication signal comprising the message.

Wireless Power Transfer Process

Referring to FIG. 2, in some embodiments, transmitting and receivingdevices 12 and 10 are configured to operate in accordance with awireless power transfer protocol 200 for initiating and controllingwireless power transfer. The power transfer protocol 200 comprises aninitiation phase 201, a handshake phase 202 and a wireless powertransfer phase 203. The process may also comprise an optionalcalibration phase (not shown in FIG. 2), but briefly described below.The phases of the process 200 may be sequential in that a previous phasemust be terminated before a current phase is initiated, or in someembodiments, one or more phases may be combined or be allowed to operatesimultaneously. One or both of transmitting or receiving devices 12 or10 may be configured to act as “initiator” of a phase and/or as“terminator” of a phase. Typically the receiving device 10 acts as the“master”.

During initiation phase 201, transmitting device 12 establishes wirelesscommunication with a receiving device 10 when receiving device 10 iswithin communication range of transmitting device 12. Transmittingdevice 12 can confirm the presence of receiving device 10 by sendinginterrogation signal(s) and listening for a response signal fromreceiving device 10, for example. Control circuitry 42 of transmittingdevice 12 can be configured to continuously or periodically generate andsend (via wireless power transmitting circuitry 34 or other wirelesscommunications circuitry), interrogation signal(s), or ping signals,during a selection or ping phase of the initiation phase 201. Controlcircuitry 20 of receiving device 10 can be configured to listen forinterrogation signal(s) from nearby transmitting device(s) 12 and togenerate and send, in response, one or more response message(s) (viawireless communications circuitry 56, for example). The responsemessage(s) may include data indicative of a received signal strength.Receiving device 10 may send further messages including identificationdata associated with receiving device 10 during an identification &configuration phase of the initiation phase 201. The message(s) may alsoinclude configuration data indicative of a desired or requiredconfiguration settings for transmitting device 12. Control circuitry 42of transmitting device 12 can be configured to receive the responsemessage(s) from receiving device 10 and determine from the messages(s)an appropriate connection for wireless power transfer. For example,control circuitry 42 may be configured to confirm the suitability of aconnection using one or more variables associated with the responsemessage(s), such as signal strength, receiver identification and/orconfiguration settings. Control circuitry 42 may also update or adjustone or more configuration parameters associated with wireless powertransfer using configuration data from the response message(s).

During or prior to initiation phase 201, transmitting device 12 may beconfigured to determine the presence of a foreign object such asbankcards, coins or other metals, in the field of magnetic flux. Controlcircuitry 42 of transmitting device 12 may only enable progression ofprocess 200 into the handshake phase 202, or any other succeedingstages, if the absence of a foreign object with adverse effects is firstconfirmed. Foreign object detection may be carried out using a number ofmethods according to the application requirements. For example,impedance or Q factor measurements, which may be measured at one or morepredetermined frequencies, over one or more ranges of frequencies, powerloss accounting, or known characteristics of foreign objects may bemonitored for.

Upon establishing a connection, connected transmitting and receivingdevices 12 and 10 can proceed into a handshake or negotiation phase 202.During handshake phase 202, transmitting and receiving devices 12 and 10communicate to establish a power transfer contract, governing one ormore conditions of power transfer for the power transfer phase 203. Thepower transfer condition(s) of the power transfer contract may comprise,for example, a maximum power transfer limit, guaranteed power, receivedpower packet (RP) format, FSK polarity and modulation depth. The powertransfer condition(s) can be stored in memory associated with controlcircuitry 42 of transmitting device 12 and used to control wirelesspower transmitting circuitry 34 during the power transfer phase 203accordingly. In some embodiments, one or more of the power transfercondition(s) may be pre-established and pre-stored in memory associatedwith control circuitry 42 of the transmitting device 12. In someembodiments, one or more of the power transfer condition(s) may becommunicated by the receiving device 10 to the transmitting device 12during handshake phase 202. In some embodiments, one or more of thepower transfer condition(s) may be determined by the transmitting device12 or receiving device 10 using on one or more operational variables ofreceiving device 10. For example, a maximum power transfer limitcondition may be determined by receiving device 10 using a state ofcharge of a battery 18 associated with receiving device 10. Thedetermined maximum power transfer limit condition can be communicated byreceiving device 10 to transmitting device 12 during the handshake phase202. Control circuitry 42 of transmitting device 12 is configured todrive wireless power transmitting circuitry 34 to transmit wirelesspower in accordance with the power transfer contract established inphase 202, during the power transfer phase 203.

In some embodiments, transmitting and receiving devices 10 and 12 may beconfigured to perform a pre-power-transfer calibration (not shown inFIG. 2). In pre-power-transfer calibration, transmitting device 12 canbe configured to subject receiving device to multiple varyingcalibration power levels, and to receive received power message(s) inresponse indicative of a level of wireless power received by receivingdevice 10. Two or more varying calibration power levels may betransmitted to receiving device 10 in this phase. Control circuitry 42can determine the calibration power levels using one or more operationalvariables associated with a load. For example, each calibration powerlevel may be determined based on a different percentage of a maximumpower consumable by the load, e.g., 10% and 100%. Other calibration loadlevels within this range may be transmitted in this phase. Controlcircuitry 42 can use the received power message(s) and associated thecalibration power levels to generate a model of expected load behavior.For example, the model may be generated using a linear regressiontechnique. The model can be stored in electronic memory associated withcontrol circuitry 42. During power transfer phase 203, control circuitry42 can use received power message(s) sent by receiving device 10 and thepre-stored model to determine the potential presence of a foreignobject. Control circuitry 42 may compare a level of received poweragainst an expected level of received power obtained from the model fora current transmission power level, and determine from the level ofdeviation a value indicative of the presence of a foreign object.Control circuitry 42 may adjust operation of wireless power transmittingcircuitry 34 and/or send message(s) to receiving device 10 upondetection of a foreign object as previously described.

During power transfer phase 203, transmitting device 12 transferswireless power to the receiving device 10 for supply to a load of thereceiving device 10, such as battery 18. Wireless power transfer issubstantially continuous in phase 203. Received wireless power may alsobe used by receiving device 10 to power other devices or circuitry inthe receiving device 10, such as wireless power receiving circuitry 46,input-output devices 22 and control circuitry 20. In phase 203, controlcircuitry 42 can be configured to generate a drive signal for wirelesspower transmitting circuitry 34 to transfer wireless power fromtransmitting device 12 to receiving device 10 in accordance with thecondition(s) of the power transfer contract established during handshakephase 202.

Wireless power is transferred from transmitting device 12 to receivingdevice 10 according to the power requirements of the receiver's load,such as the charging requirements of a battery 18. Receiving device 10can be configured to generate feedback message(s) indicative of a levelof deviation between received power and a desired power requirement ofthe load. The feedback message(s) such as control error (CE) packets maybe communicated to transmitting device 12 for adjusting a level oftransferred wireless power accordingly, if necessary. Control circuitry42 of transmitting device 12 can be configured to receive feedbackmessage(s) and to adjust a driving signal (in amplitude, duty cycle,phase or frequency) for wireless power transmitting circuitry 34 usingthe feedback message(s) to reduce the level of deviation towards zero.The feedback message(s) may be generated periodically by controlcircuitry 20 during power transfer phase 203.

Control circuitry 20 of receiving device 10 is also configured togenerate received power message(s) using the receiving circuitry 46, andto send the received power message(s) to transmitting device 12 usingwireless communication circuitry 56. The received power P_(PR) (RP)message(s) can indicate of a level of power received by coil(s) 14,including associated power loss. This may be determined empiricallyusing a test setup and may take into account the power P_(out) providedat the receiver output and adding any power P_(PRloss) that is lostinside the receiver device. This power P_(PRloss) may include, forexample: the power loss in the rectifier, the power loss in the receivercoil, the power loss in the resonance capacitor, the power loss in theshielding of the receiver assembly, and the power loss in any metalparts of the receiver). The received power message(s) may be sentperiodically during calibration or power transfer phase 203. Controlcircuitry 42 of transmitting device 12, can be configured to receive thereceived power message(s) and to determine, using the received powermessage(s), the potential presence of a foreign object. For example,control circuitry 42 may compare the level of received power to apredetermined expected level of received power stored in associatedmemory to determine the presence of an unwanted foreign object. Upondetection of a foreign object, control circuitry 42 may reducetransmitted power to a safe level or terminate wireless power transferby driving wireless power transmitting circuitry 34 accordingly.

In some embodiments, transmitting and receiving devices 12 and 10 may beconfigured to terminate a power transfer phase 203 and to return to ahandshake phase 202 to establish a new power transfer contract, ifprompted by one of the devices 12 or 10. In some embodiments, either oneof transmitting or receiving device 12 or 10 may be configured toterminate power transfer phase 203 and reinitiate handshake phase 202.In other embodiments, only one of transmitting or receiving device 12 or10 may be configured to terminate power transfer phase 203 andreinitiate handshake phase 202. For example, receiving device 10 may beconfigured to terminate a power transfer phase 203 and re-initiate ahandshake phase 202 when a desired power requirement of an associatedload, such as battery 18, is outside a threshold value or range of acurrent power transfer contract.

Referring to FIG. 3 a further example protocol 300 is shown forinitiating and controlling power transfer. Initially if an object isdetected 301 the transmitter sends a ping 302 using the powertransmitting coil. The ping is typically an analogue signal that wakes areceiver if that is the adjacent object. This is followed by a digitalping from the transmitter, and a compatible receiver then replies with asignal strength packet. If the signal strength packet is valid, thepower transmitter proceeds to the next phase. The receiver then replies304 with a configuration packet, and identification packet. Theconfiguration packet includes a number of flag bits for variousscenarios. If the “negotiation” bit is false 306, the transmitter beginspower transfer 328 under the basic power profile (BPP) 308.

If the “negotiation” bit is true 310, the transmitter and receiver entera negotiation phase 312, with the transmitter responding with a FSKresponse pattern. If the negotiation is successful 314, then thetransmitter enters a power calibration phase 316. If the calibration issuccessful 318, the transmitter begins power transfer 328 under theextended power profile (EPP) 320.

A Boolean true signal can be a signal that represents a binary of “one”,a voltage signal exceeding a threshold, a pattern of specific binary bitvalues, or other values representative of true depending on therequirements of the application. Conversely a Boolean false signal canbe a signal that represents a binary of “zero”, a voltage signal below athreshold, a pattern of specific binary bit values, or other valuesrepresentative of false depending on the requirements of theapplication.

For a power receiver that supports performing the calibration phase 316it begins sending message packets (RP) containing the received powerwith a mode such as binary “001” denoting a light load power level untilthe power transmitter acknowledges that it has finished calibration inthis mode with a light load power. Subsequently the power receiverbegins sending RP packets containing the received power with a mode suchas binary “010” denoting a connected load until the power transmitteracknowledges that it has finished calibration in this mode with aconnected load. If the second (e.g. binary “010”) mode is successfullycompleted and acknowledged to the power receiver by the powertransmitter, the power receiver will proceed with power transfer wheremessage packets containing received power with a mode such as “000” areused.

If the configuration, negotiation, calibration, or power transfer phasesreturn an error condition, then the process resets 330 and begins fromthe start.

Cloaking During Power Transfer Phase

Referring to FIG. 4, in some embodiments, control circuitry 20 ofreceiving device 10 is configured to temporarily disable power transferduring power transfer phase 203, to “cloak” the receiver. In thismanner, during the cloak state 400, the receiving device 10 sends an EndPower Transfer message 402 (as defined in the table below) to thetransmitter device 12, to start the period where the transmitter deviceenters a low power or non-transmitting state 404. This may occur whenthe wireless power receiving device has reached temperature thresholdlimit, and it would be desirable for the transmitting device, thereceiving device 10, or both, to appear as if charging is stilloccurring. After cooling down during the cloak state 400, wireless powertransmission can resume.

Qi 1.2.3 provides for a number of different end power transfer packetcodes. For example currently 0x0C to 0xFF are reserved for futurefunctionality. The receiving device 10 may send a Re-ping after End ofPower Transfer (EPT/rep) packet using reserved EPT code 0x0C. This willinclude a value for a negotiated period t_(reping), that thetransmitting device 12 will deactivate, or enter a low power state 404,before sending a new digital ping 406. It may be desirable for theamount of heat generated by the transmitting device 12 to be reducedduring the low power state 404. After each digital ping 406 thereceiving device 10 waits t_(wake) for the voltage to stabilize, beforesending a message. This may be EPT/rep if it wants to stay cloaked, or anumber of other message types 408, as described below, if it wants toexit cloaking 410.

Referring to FIG. 5 the transmitting device 12 may wish to initiate acommunication channel with the receiving device 10 during the cloakingstate. It can be useful for the transmitting and receiving devices toperform some communication even though the receiving device istemporarily not needing wireless power.

For example, the transmitting and receiving devices may communicate andagree on a coordinated user interface experience. Consider the situationin which both the transmitting and receiving devices are capable ofdisplaying charge-in-progress indicators using an LED and a touchscreen,respectively. If EPT/re-ping packets are being communicated on the orderof milliseconds, it would improve the user's experience if the twodevices can agree on avoiding repeated updates of the charge-in-progressindicators at the milliseconds frequency, and instead to providecoordinated updates at a more user perceptible rate, (e.g., afterseconds repeatedly, to provide a longer duration of cloaking, it may bethe cloaking period on the order of milliseconds).

In a further example, the transmitting device 12 may wish to inform thereceiving device 10 that the transmitting device 12 has started aterminal shutdown event, perhaps because of impending loss of inputpower (e.g. unplugged). In this scenario the receiving device 10 mightnot deduce this for up to 12.6 sec (when it expects to be re-pinged bythe transmitting device 12), but by being informed early by means of thecommunication channel, prompt and intuitive change of state can beprovided in the user interface on the receiving device 10. Other eventscould include detection of a foreign object that will now inhibitcontinued charging (in which case prompt, intuitive change of state canbe provided to the user interface instead of waiting to deduce that thetransmitting device fails to resume on schedule in up to 12.6 sec).

After t_(response) from the EPT/rep, the transmitting device 12 sendsand acknowledgement (ACK), indicating it wants to initiate acommunication channel. If the receiving device 10 is able to proceedwith communication, it will send a data stream request (DSR) packet toconfirm this. In the case of a basic power profile (BPP) one way ASKcomms from device 10 to device 12 is possible. In the case of anextended power profile (EPP) two way amplitude-shift key/frequency-shiftkey (ASK/FSK) comms between device 10 and device 12 is possible. Oncethe data stream is established, the transmitting device 12 may requestfor the receiving device 10 user interface (UI) to inhibit or disablethe chime, prevent changing the charging light, or prevent changing anyicons on the screen, that would normally occur when power transfer ends.

If the receiving device 10 wishes to initiate a communication channelwith the transmitting device 12 during the cloaking state, it may comeout of cloaking to communicate with the transmitting device 12, bysending a Specific Request (GSR) packet (such as using reserved bit0x05) which may include a request for the transmitting device 12 UI toinhibit or disable the charging light changing, that would normallyoccur when power transfer ends.

If instead, where the transmitting device 12 wishes to initiate acommunication channel, the receiving device 10 may deny this as shown inFIG. 6. This may occur, where the receiving device 10 is in a criticaltemperature state and cannot permit any further heating at all. Aftert_(response) the transmitting device 12 sends ACK, indicating it wantsto initiate a communication channel, and the receiving device 10 sends adeny communications end of power transfer packet (EPT/dny) usingreserved bit 0x0E to deny the request. The transmitting device 12 willdeactivate, or enter a low power state for t_(reping), before sending anew digital ping.

In the event that the initial ACK is not received from the transmittingdevice 12 within t_(terminate) and that the digital ping signal is stillpresent (indicating that the transmitting device is still attempting tocommunicate), the receiving device 10 resends the EPT/rep, as shown inFIG. 7. If the subsequent ACK is received, the protocol proceeds as perFIG. 6.

Similarly if the initial EPT/rep is not received from the receivingdevice 10, and as a result not response is received from thetransmitting device 12 within t_(terminate)+t_(EPT), and that thedigital ping signal is still present (indicating that the transmittingdevice is still attempting to communicate), the receiving device 10resends the EPT/rep, as shown in FIG. 8. If the subsequent ACK isreceived, the protocol proceeds as per FIG. 6.

Referring to FIG. 9 if the receiving device 10 wishes to initiate animmediate resumption of power transfer using the previously agreed powercontract with the transmitting device 12, it may use a hot startprotocol. In order to ensure that receiving device 10 or transmittingdevice 12 have not changed, e.g.: if a new receiving device 10 isintroduced or if a receiving device 10 is swapped between transmittingdevices 12, it may be necessary to interchange identity details toverify that neither party has changed. After the digital ping 406, thereceiving device 10 waits t_(wake) for the voltage to stabilize, beforesending a RxID packet. The ID value may be the pseudo unique BasicDevice Identifier from the ID packet. After t_(response) thetransmitting device 12 sends ACK if it is able to proceed with hotstart, then the receiving device 10 sends a general request packetrequesting the transmitter identity (GRQ/id). After t_(response) thetransmitting device 12 sends a Power Transmitter Identification Packet(TxID) (0x30) including the “Basic Device Identifier” in bytes B3, . . ., B6; defined in the same way for the power receiver's Identificationpacket (a 32 bit arbitrary number/string, of which at least 20 bits mustbe unique to the unit i.e. random serial number). Alternatively a newunit identification (serial) number packet could be defined e.g., newpacket type 0x32 “Unit Number” to contain a 32/24/16 bit (4/3/2 byte)serial number. If this is completed successfully the transmitting device12 will resume power transfer 900 using the previously agreed powercontract.

Similarly as shown in FIG. 10 if the initial RxID packet is not receivedby the transmitting device 12, and the receiving device 10 does notreceive a response, the receiving device 10 will resend the RxID packetafter waiting t_(start). In that case, if the subsequent RxID packet isreceived by the transmitting device 12, the protocol proceeds as perFIG. 9.

In the event that the initial RxID packet is not received by thetransmitting device 12, and at least one further (for example twofurther) RxID packet is not received by the transmitting device 12, thenafter t_(cloaktimeout) the transmitting device 12 will deactivate as perFIG. 11.

As described above, one aspect of the present technology relates to datacommunications between a wireless power transmitter and a wireless powerreceiver. In some instances, this data communication can include a BasicDevice Identifier and Power Transmitter Identification Packet.

The use of such device identification data in the present technology canbe used to the benefit of users. For example, it can be helpful for awireless power transmitter to understand whether back-to-back datapackets are being sent by the same wireless power receiver device, or ifwireless power receiver devices have been swapped. The presentdisclosure recognizes that the communication of identificationinformation, even if the identification information is not globallyunique, may be perceived as the obtaining of personal information data.

It is thus recommended that entities responsible for the collection,analysis, disclosure, transfer, storage, or other use of suchinformation data comply with well-established privacy policies and/orprivacy practices. In particular, such entities should implement andconsistently use privacy policies and practices that are generallyrecognized as meeting or exceeding industry or governmental requirementsfor maintaining personal information data private and secure. Suchpolicies should be easily accessible by users and should be updated asthe collection and/or use of data changes. Personal information fromusers should be collected for legitimate and reasonable uses of theentity and not shared or sold outside of those legitimate uses. Further,such collection/sharing should occur after receiving the informedconsent of the users. Additionally, such entities should consider takingany needed steps for safeguarding and securing access to such personalinformation data and ensuring that others with access to the personalinformation data adhere to their privacy policies and procedures.Further, such entities can subject themselves to evaluation by thirdparties to certify their adherence to widely accepted privacy policiesand practices. In addition, policies and practices should be adapted forthe particular types of personal information data being collected and/oraccessed and adapted to applicable laws and standards, includingjurisdiction-specific considerations. For instance, in the US,collection of or access to certain health data may be governed byfederal and/or state laws, such as the Health Insurance Portability andAccountability Act (HIPAA); whereas health data in other countries maybe subject to other regulations and policies and should be handledaccordingly. Hence different privacy practices should be maintained fordifferent data types in each country.

Despite the foregoing, the present disclosure also contemplatesembodiments in which users selectively block the use of, or access to,information data such as those described above with respect to FIGS. 9to 11. That is, the present disclosure contemplates that hardware and/orsoftware elements can be provided to prevent or block access to suchpersonal information data. For example, the present technology can beconfigured to allow users to select to “opt in” or “opt out” ofparticipation in the collection of personal information data duringregistration for services or anytime thereafter. In another example,users can select the specific services and functions that personalinformation data will be used for. In yet another example, users canselect to limit the length of time that personal data is stored or usedfor specific services and functions. In addition to providing “opt in”and “opt out” options, the present disclosure contemplates providingnotifications relating to the access or use of personal information. Forinstance, a user may be notified upon downloading an app that theirpersonal information data will be accessed and then reminded again justbefore personal information data is accessed by the app.

Moreover, it is the intent of the present disclosure that identificationinformation data should be managed and handled in a way to minimizerisks of unintentional or unauthorized access or use. Risk can beminimized by limiting the collection of data and deleting data once itis no longer needed. In addition, and when applicable, including incertain health related applications, data de-identification can be usedto protect a user's privacy. De-identification may be facilitated, whenappropriate, by removing specific identifiers and controlling the amountor specificity of data stored (e.g., removing some bits out of a largeridentification string and not using globally unique identificationcodes), controlling how data is stored (e.g., aggregating data acrossusers), and/or other methods.

Referring to FIG. 12 if a cloaked receiving device is replaced by anuncloaked receiving device which was in power transfer phase, thetransmitting device 12 will deactivate or terminate. For example aftert_(reping) and t_(wake), if the expected SSI, RxID or EPT/rep is notreceived, and instead a CE, RP or other unexpected packet is received,the transmitting device 12 will deactivate. Similarly if the first CE,RP or other unexpected packet is not received by the transmitting device12, and if the subsequent CE or RP packet is received by thetransmitting device 12, the transmitting device 12 will or revert/resetto a default/first time operating state or initialize as per FIG. 12.

The foregoing is merely illustrative and various modifications can bemade to the described embodiments. The foregoing embodiments may beimplemented individually or in any combination, and elements from oneembodiment may be combined with others.

The invention claimed is:
 1. A wireless power receiver comprising: awireless power receiving coil; wireless power receiving circuitrycoupled to the wireless power receiving coil; wireless communicationcircuitry that communicates with a wireless power transmitter; andwireless power receiver control circuitry that controls the wirelesspower receiving circuitry and the wireless communication circuitry,wherein the wireless power receiver control circuitry is configured toinitiate a cloaking state during which power transfer from the wirelesspower transmitter is temporarily disabled by using the wirelesscommunication circuitry to send a message to the wireless powertransmitter to start a period during which the wireless powertransmitter enters a low power or non-transmitting state and wherein thewireless power receiver control circuitry is further configured torespond to a request from the wireless power transmitter to re-initiatecommunications or power transfer by: using the wireless communicationcircuitry to send a message to the wireless power transmitter indicatingthat the wireless power receiver wants to remain in the cloaking state;or using the wireless communication circuitry to send a messageindicating that the wireless power receiver wants to exit the cloakingstate.
 2. The wireless power receiver of claim 1 wherein the wirelesspower receiver control circuitry initiates the cloaking state inresponse to a temperature threshold limit.
 3. The wireless powerreceiver of claim 1 wherein the message to the wireless powertransmitter to start a period during which the wireless powertransmitter enters a low power or non-transmitting state is an end powertransfer re-ping (EPT/rep) packet.
 4. The wireless power receiver ofclaim 1 wherein the message to the wireless power transmitter to start aperiod during which the wireless power transmitter enters a low power ornon-transmitting state includes a value corresponding to a time that thewireless power transmitter will remain in the low power ornon-transmitting state before attempting to re-initiate communicationsor power transfer.
 5. The wireless power receiver of claim 1 wherein themessage to the wireless power transmitter indicating that the wirelesspower receiver wants to remain in the cloaking state is an end powertransfer re-ping (EPT/rep) packet.
 6. The wireless power receiver ofclaim 1 wherein the wireless power receiver control circuitry is furtherconfigured to use the communication circuitry to communicate with thewireless power transmitter to agree on a coordinated user interfaceexperience.
 7. The wireless power receiver of claim 6 wherein the agreedcoordinated user interface experience relates to coordinated updates ofcharge in progress indicators.
 8. The wireless power receiver of claim 6wherein the agreed coordinated user interface experience relates to aterminal shutdown event of the wireless power transmitter.
 9. Thewireless power receiver of claim 6 wherein the agreed coordinated userinterface experience relates to detection of a foreign object.
 10. Thewireless power receiver of claim 6 wherein the agreed coordinated userinterface experience includes one or more of: inhibiting or disabling achime, preventing changing of a charging light, and preventing changingany icons on a display screen.
 11. The wireless power receiver of claim6 wherein the wireless power receiver control circuitry is configured touse the wireless communication circuitry to send a message to thewireless power transmitter to establish a communication channel with thewireless power transmitter.
 12. The wireless power receiver of claim 11wherein the message is a specific request (GSR) packet.
 13. The wirelesspower receiver of claim 1 wherein the wireless power receiver controlcircuitry is further configured to exit the cloaking state and resumepower transfer from the wireless power transmitter by using the wirelesscommunication circuitry to: send a first set of messages to the wirelesspower transmitter to resume power transfer using a previously agreedpower contract; or send a second set of messages to the wireless powertransmitter to renegotiate a power contract and resume power transfer.14. The wireless power receiver of claim 13 wherein the first set ofmessages includes a receiver identification (RxID) packet and a generalrequest packet (GRQ/id) requesting an identity of the wireless powertransmitter.
 15. The wireless power receiver of claim 13 wherein thesecond set of messages includes an unexpected packet other than a signalstrength indicator packet (SSI), a receiver identifier packet (RxID), orand end power transfer re-ping packet (EPT/rep).
 16. The wireless powerreceiver of claim 15 wherein the unexpected packet is a control errorpacket (CE).
 17. The wireless power receiver of claim 15 wherein theunexpected packet is a received power (RP) packet.
 18. A wireless powertransmitter comprising: a wireless power transmitting coil; wirelesspower transmitting circuitry coupled to the wireless power receivingcoil; wireless power transmitter control circuitry that controls thewireless power transmitting circuitry, wherein the wireless powertransmitter control circuitry is configured to initiate a cloaking stateduring which power transfer from the wireless power transmitter istemporarily disabled responsive to a message from the wireless powerreceiver to start a period during which the wireless power transmitterenters a low power or non-transmitting state and wherein the powertransmitter control circuitry is further configured to send a requestfrom the wireless power transmitter to re-initiate communications orpower transfer and receiving in response thereto a first messageindicating that the wireless power receiver wants to remain in thecloaking state, in which case the wireless power transmitter controlcircuitry cause the wireless power transmitter to remain in the cloakingstate, or a second message indicating that the wireless power receiverwants to exit the cloaking state in which the wireless power transmittercontrol circuitry causes the wireless power transmitter to exit thecloaking state.
 19. The wireless power transmitter of claim 18 whereinthe message from the wireless power receiver to start a period duringwhich the wireless power transmitter enters a low power ornon-transmitting state is an end power transfer re-ping (EPT/rep)packet.
 20. The wireless power transmitter of claim 18 wherein themessage from the wireless power receiver to start a period during whichthe wireless power transmitter enters a low power on non-transmittingstate includes a value corresponding to a time that the wireless powertransmitter will remain in the low power or non-transmitting statebefore attempting to re-initiate communications or power transfer. 21.The wireless power transmitter of claim 18 wherein the wireless powertransmitter control circuitry is further configured to use thecommunication circuitry to communicate with the wireless power receiverto agree on a coordinated user interface experience.
 22. The wirelesspower transmitter of claim 21 wherein the agreed coordinated userinterface experience relates to coordinated updates of charge inprogress indicators.
 23. The wireless power transmitter of claim 21wherein the agreed coordinated user interface experience relates to aterminal shutdown event of the wireless power transmitter.
 24. Thewireless power transmitter of claim 21 wherein the agreed coordinateduser interface experience relates to detection of a foreign object. 25.The wireless power transmitter of claim 21 wherein the agreedcoordinated user interface experience includes one or more of:inhibiting or disabling a chime, preventing changing of a charginglight, and preventing changing any icons on a di splay screen.
 26. Thewireless power transmitter of claim 21 wherein the wireless powertransmitter control circuitry is configured to use the wirelesscommunication circuitry to send a message to the wireless powertransmitter to establish a communication channel with the wireless powertransmitter.
 27. The wireless power transmitter of claim 26 wherein themessage is a specific request (GSR) packet.
 28. The wireless powertransmitter of claim 18 wherein the wireless power transmitter controlcircuitry is further configured to exit the cloaking state and resumepower transfer to the wireless power receiver responsive to at least oneof: a first set of messages from the wireless power receiver to resumepower transfer using a previously agreed power contract; or a second setof messages from the wireless power receiver to renegotiate a powercontract and resume power transfer.
 29. The wireless power transmitterof claim 28 wherein the first set of messages includes a receiveridentification (RxID) packet and a general request packet (GRQ/id)requesting an identity of the wireless power transmitter.
 30. Thewireless power transmitter of claim 28 wherein the second set ofmessages includes an unexpected packet other than a signal strengthindicator packet (SSI), a receiver identifier packet (RxID), or and endpower transfer re-ping packet (EPT/rep).
 31. The wireless powertransmitter of claim 30 wherein the unexpected packet is a control errorpacket (CE).
 32. The wireless power transmitter of claim 30 wherein theunexpected packet is a received power (RP) packet.
 33. A wireless powerreceiver comprising: a wireless power receiving coil; wireless powerreceiving circuitry coupled to the wireless power receiving coil;wireless communication circuitry that communicates with a wireless powertransmitter; and wireless power receiver control circuitry that controlsthe wireless power receiving circuitry and the wireless communicationcircuitry, wherein the wireless power receiver control circuitry isconfigured to initiate a cloaking state during which power transfer fromthe wireless power transmitter is temporarily disabled by using thewireless communication circuitry to send a message to the wireless powertransmitter to start a period during which the wireless powertransmitter enters a low power or non-transmitting state and wherein thewireless power receiver control circuitry is further configured to exitthe cloaking state and resume power transfer from the wireless powertransmitter by using the wireless communication circuitry to: send afirst set of messages to the wireless power transmitter to resume powertransfer using a previously agreed power contract; or send a second setof messages to the wireless power transmitter to renegotiate a powercontract and resume power transfer.
 34. The wireless power receiver ofclaim 33 wherein the wireless power receiver control circuitry initiatesthe cloaking state in response to a temperature threshold limit.
 35. Thewireless power receiver of claim 33 wherein the message to the wirelesspower transmitter to start a period during which the wireless powertransmitter enters a low power or non-transmitting state is an end powertransfer re-ping (EPT/rep) packet.
 36. The wireless power receiver ofclaim 33 wherein the message includes a value corresponding to a timethat the wireless power transmitter will remain in the low power ornon-transmitting state before attempting to re-initiate communicationsor power transfer.
 37. The wireless power receiver of claim 33 whereinthe wireless power receiver control circuitry is further configured touse the communication circuitry to communicate with the wireless powertransmitter to agree on a coordinated user interface experience.
 38. Thewireless power receiver of claim 37 wherein the agreed coordinated userinterface experience relates to coordinated updates of charge inprogress indicators.
 39. The wireless power receiver of claim 37 whereinthe agreed coordinated user interface experience relates to a terminalshutdown event of the wireless power transmitter.
 40. The wireless powerreceiver of claim 37 wherein the agreed coordinated user interfaceexperience relates to detection of a foreign object.
 41. The wirelesspower receiver of claim 37 wherein the agreed coordinated user interfaceexperience includes one or more of: inhibiting or disabling a chime,preventing changing of a charging light, and preventing changing anyicons on a display screen.
 42. The wireless power receiver of claim 37wherein the wireless power receiver control circuitry is configured touse the wireless communication circuitry to send a message to thewireless power transmitter to establish a communication channel with thewireless power transmitter.
 43. The wireless power receiver of claim 42wherein the message is a specific request (GSR) packet.
 44. The wirelesspower receiver of claim 33 wherein the first set of messages includes areceiver identification (RxID) packet and a general request packet(GRQ/id) requesting an identity of the wireless power transmitter. 45.The wireless power receiver of claim 33 wherein the second set ofmessages includes an unexpected packet other than a signal strengthindicator packet (SSI), a receiver identifier packet (RxID), or and endpower transfer re-ping packet (EPT/rep).
 46. The wireless power receiverof claim 45 wherein the unexpected packet is a control error packet(CE).
 47. The wireless power receiver of claim 45 wherein the unexpectedpacket is a received power (RP) packet.
 48. A wireless power transmittercomprising: a wireless power transmitting coil; wireless powertransmitting circuitry coupled to the wireless power receiving coil;wireless power transmitter control circuitry that controls the wirelesspower transmitting circuitry, wherein the wireless power transmittercontrol circuitry is configured to initiate a cloaking state duringwhich power transfer from the wireless power transmitter is temporarilydisabled responsive to a message from the wireless power receiver tostart a period during which the wireless power transmitter enters a lowpower or non-transmitting state and wherein the wireless powertransmitter control circuitry is further configured to exit the cloakingstate and resume power transfer to the wireless power receiverresponsive to at least one of: a first set of messages from the wirelesspower receiver to resume power transfer using a previously agreed powercontract; or a second set of messages from the wireless power receiverto renegotiate a power contract and resume power transfer.
 49. Thewireless power transmitter of claim 48 wherein the message from thewireless power receiver to start a period during which the wirelesspower transmitter enters a low power or non-transmitting state is an endpower transfer re-ping (EPT/rep) packet.
 50. The wireless powertransmitter of claim 48 wherein the message from the wireless powerreceiver to start a period during which the wireless power transmitterenters a low power on non-transmitting state includes a valuecorresponding to a time that the wireless power transmitter will remainin the low power or non-transmitting state before attempting tore-initiate communications or power transfer.
 51. The wireless powertransmitter of claim 48 wherein the wireless power transmitter controlcircuitry is further configured to use the communication circuitry tocommunicate with the wireless power receiver to agree on a coordinateduser interface experience.
 52. The wireless power transmitter of claim51 wherein the agreed coordinated user interface experience relates tocoordinated updates of charge in progress indicators.
 53. The wirelesspower transmitter of claim 51 wherein the agreed coordinated userinterface experience relates to a terminal shutdown event of thewireless power transmitter.
 54. The wireless power transmitter of claim51 wherein the agreed coordinated user interface experience relates todetection of a foreign object.
 55. The wireless power transmitter ofclaim 51 wherein the agreed coordinated user interface experienceincludes one or more of: inhibiting or disabling a chime, preventingchanging of a charging light, and preventing changing any icons on adisplay screen.
 56. The wireless power transmitter of claim 51 whereinthe wireless power transmitter control circuitry is configured to usethe wireless communication circuitry to send a message to the wirelesspower transmitter to establish a communication channel with the wirelesspower transmitter.
 57. The wireless power transmitter of claim 56wherein the message is a specific request (GSR) packet.
 58. The wirelesspower transmitter of claim 48 wherein the first set of messages includesa receiver identification (RxID) packet and a general request packet(GRQ/id) requesting an identity of the wireless power transmitter. 59.The wireless power transmitter of claim 48 wherein the second set ofmessages includes an unexpected packet other than a signal strengthindicator packet (SSI), a receiver identifier packet (RxID), or and endpower transfer re-ping packet (EPT/rep).
 60. The wireless powertransmitter of claim 59 wherein the unexpected packet is a control errorpacket (CE).
 61. The wireless power transmitter of claim 59 wherein theunexpected packet is a received power (RP) packet.